Damping devices which are situated between a housing wall and a casing ring or casing ring segment of thermal gas turbines for the purpose of reducing a heat input into the housing wall during operation of the associated gas turbine are present in environments having high temperature gradients. These components are therefore designed in such a way that the deformation which is generated by the temperature gradient does not or essentially does not impair the damping function.
A damping device is known from DE 43 31 060 C1 which includes two metal foils which are connected to one another by crimping over their edge areas and which include a heat insulating material. The heat insulating material is, for example, a compact composite material mixture of a not-expanded aluminum silicate/ceramic fiber/vermiculite and an organic binder. Rising temperatures result in an expansion of the heat insulating material so that the damping device is pressed against the walls which delimit the hollow space, thus additionally sealing the latter. The crimping over of the metal foils may result in them shifting against one another during the volume increase in the heat insulating material.
The circumstance to be considered as disadvantageous in the case of the known damping device is that the metal foils which are to be provided to be relatively thin are susceptible to cracking, in particular in the transition area to their crimping lines, as well as on their radial bottom side which faces the hot gas of the gas turbine.
The heat insulating material is lost over time due to the resulting cracks, whereby both the damping and the sealing effects are impaired.